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When early explorers sailed to foreign shores, they drew maps to chart the size and shape of the lands that they found. We still explore in this way, but on a much larger scale. Although we’ve charted most of the Earth, we have only started exploring beyond our planet. By mapping the size and shape of our solar system, galaxy and the universe, we’re beginning to chart our place in the cosmos.

Orreries show the rates at which the different planets move around the Sun. They are named after Charles Boyle, the fourth Earl of Orrery, as he commissioned one of the earliest of these models.

This information is from the exhibition "By the light of the southern stars" at Sydney Observatory, part of the Powerhouse Museum.

When early explorers sailed to foreign shores, they drew maps to chart the size and shape of the lands that they found. We still explore in this way, but on a much larger scale. Although we’ve charted most of the Earth, we have only started exploring beyond our planet. By mapping the size and shape of our solar system, galaxy and the universe, we’re beginning to chart our place in the cosmos.

Orreries show the rates at which the different planets move around the Sun. They are named after Charles Boyle, the fourth Earl of Orrery, as he commissioned one of the earliest of these models.

This information is from the exhibition "By the light of the southern stars" at Sydney Observatory, part of the Powerhouse Museum.

Celestial globes are a popular way of mapping the positions of the stars. The shape of the globe matches the curved appearance of the sky. Map makers often decorate celestial globes with drawings of the constellations.

Celestial globes are a popular way of mapping the positions of the stars. The shape of the globe matches the curved appearance of the sky. Map makers often decorate celestial globes with drawings of the constellations.

A transit of Venus takes place when the planet crosses the disc of the Sun as seen from Earth. Such transits occur in pairs eight years apart, separated by a century or so. To astronomers of the 18th and 19th centuries they were of crucial importance as they provided a method of determining the distance between the Earth and Sun, and hence the scale of the Solar System.

Australia has a close connection with this rare astronomical event through Captain James Cook who mapped the continent’s east coast on his way back to Britain after observing the transit of 1769 from Tahiti. When the next transit occurred in 1874, Sydney Observatory was in an ideal position to make detailed observations.

Henry Chamberlain Russell started preparing for the 1874 transit immediately on becoming Government Astronomer in 1870. He purchased new telescopes and recruited a team of observers. Among them were the Reverend W. Scott, the first Government Astronomer, Philip F Adams, the Surveyor-General, Professor Archibald Liversidge who helped to establish the museum that eventually became the Powerhouse and the instrument maker Angelo Tornaghi. These observers went to a number o Read More

A transit of Venus takes place when the planet crosses the disc of the Sun as seen from Earth. Such transits occur in pairs eight years apart, separated by a century or so. To astronomers of the 18th and 19th centuries they were of crucial importance as they provided a method of determining the distance between the Earth and Sun, and hence the scale of the Solar System.

Australia has a close connection with this rare astronomical event through Captain James Cook who mapped the continent’s east coast on his way back to Britain after observing the transit of 1769 from Tahiti. When the next transit occurred in 1874, Sydney Observatory was in an ideal position to make detailed observations.

Henry Chamberlain Russell started preparing for the 1874 transit immediately on becoming Government Astronomer in 1870. He purchased new telescopes and recruited a team of observers. Among them were the Reverend W. Scott, the first Government Astronomer, Philip F Adams, the Surveyor-General, Professor Archibald Liversidge who helped to establish the museum that eventually became the Powerhouse and the instrument maker Angelo Tornaghi. These observers went to a number of observing stations scattered around New South Wales - Sydney Observatory itself, Eden, Goulburn and Woodford in the Blue Mountains - so as to maximise the chance of getting a clear sky at least at one site.

On the day of the transit the weather was fine at all locations except at Eden on the south coast. Russell wrote that, ’Never perhaps in the world’s history, did morning dawn on so many waiting astronomers as it did on the 9th of December, 1874’. Although atmospheric effects such as shading between the edge of the planet and the Sun made observing difficult, good results were obtained.

After the transit Russell left for England, taking with him the reports and observations of all his observers. These he handed to the Astronomer Royal who was arranging the analysis of all the observations made in the British Empire. Many years later, in 1892, Russell published a beautifully illustrated book with the complete details of all the observations that he and his observers had made.

Using radio telescopes, astronomers are mapping the gas and dust in the Milky Way to learn more about stars, galaxies and our own origins.

Everyone knows that there are stars and planets in space, but what about in between? Although it might look like a dark void, there is matter between the stars. Astronomers call this matter the interstellar medium, and it’s a mixture of gas and tiny dust particles. Out of this material, stars are continually forming-some big, some small and some medium-sized , like our Sun.

A project called the International Galactic Plane Survey (IGPS) is using radio surveys to map the interstellar medium. It started as a Canadian effort to map the section of the Milky Way visible from the Northern Hemisphere. The results were so good that American and Australian partners started a similar project for the southern hemisphere, and eventually they joined forces.

Using radio telescopes, astronomers are mapping the gas and dust in the Milky Way to learn more about stars, galaxies and our own origins.

Everyone knows that there are stars and planets in space, but what about in between? Although it might look like a dark void, there is matter between the stars. Astronomers call this matter the interstellar medium, and it’s a mixture of gas and tiny dust particles. Out of this material, stars are continually forming-some big, some small and some medium-sized , like our Sun.

A project called the International Galactic Plane Survey (IGPS) is using radio surveys to map the interstellar medium. It started as a Canadian effort to map the section of the Milky Way visible from the Northern Hemisphere. The results were so good that American and Australian partners started a similar project for the southern hemisphere, and eventually they joined forces.

For the really big picture, astronomers are making a 3-dimensional (3-D) map of the galaxies. Already they’ve charted the positions of 220 000 galaxies-just a fraction of what’s out there.

From 1997 to 2001, the Anglo-Australian telescope in eastern Australia carried out what was then the world’s largest survey of galaxies, the 2dF (two-degree field) Galaxy Redshift Survey. The 2dF survey mapped the 3-D positions in space of more than 220000 galaxies, and gave us the most detailed map of the Universe to date.

The 2dF instrument captures the light from up to 400 galaxies at a time, using 400 optical fibres - one for each galaxy to be observed. A robotic arm positions the ends of the fibres, which have little lenses on them, onto the telescope’s ’focal plate’, which is where the light coming into the telescope is focused to. Each fibre is placed so that it catches the light from one galaxy.The fibres carry the light from each galaxy into one of two spectrographs. The spectrographs split the light into its component colours. By analyzing these colours, astronomers can tell how far away a galaxy is.

For the really big picture, astronomers are making a 3-dimensional (3-D) map of the galaxies. Already they’ve charted the positions of 220 000 galaxies-just a fraction of what’s out there.

From 1997 to 2001, the Anglo-Australian telescope in eastern Australia carried out what was then the world’s largest survey of galaxies, the 2dF (two-degree field) Galaxy Redshift Survey. The 2dF survey mapped the 3-D positions in space of more than 220000 galaxies, and gave us the most detailed map of the Universe to date.

The 2dF instrument captures the light from up to 400 galaxies at a time, using 400 optical fibres - one for each galaxy to be observed. A robotic arm positions the ends of the fibres, which have little lenses on them, onto the telescope’s ’focal plate’, which is where the light coming into the telescope is focused to. Each fibre is placed so that it catches the light from one galaxy.The fibres carry the light from each galaxy into one of two spectrographs. The spectrographs split the light into its component colours. By analyzing these colours, astronomers can tell how far away a galaxy is.

The 2dF team made some astounding findings. They gathered evidence showing how the universe’s mysterious ’dark matter’ is distributed, and how giant superclusters of galaxies evolve over time due to gravity. In 2002, they found independent evidence to support the controversial idea that the universe is accelerating faster and faster, like a runaway car.

The 2dF survey was an international collaboration of more than 30 scientists from 11 institutions. In Australia, the Anglo-Australian Observatory, the Australian National University and the University of NSW were involved.